the difference between The best and Best

[manhhiep2509]

these are some examples of each of such usage:

Mother knows best.
It is best to sit while on the bus.

He is the best student in the physics class.

Please explain the difference between the best and best.
Is it correct if "best" appear in a answer choice in a Gmat sentence correction?

Thank you!

[RonPurewal]

Distinctions involving "a"/"an"/"the" are not tested on the GMAT.